While adverse selection problems between insureds and insurers are well known to insurance researchers, few explore adverse selection in the insurance industry from a capital markets perspective. This study examines adverse selection in the quoted prices of insurers' common stocks with a particular focus on the opacity of both asset portfolios and underwriting liabilities. We find that more opaque underwriting lines result in greater adverse selection costs for property-casualty (P-C) insurers. A similar effect is not apparent for life-health (L-H) insurers and we find no effect of asset opaqueness on adverse selection for either L-H or P-C insurers. Copyright (c) The Journal of Risk and Insurance, 2009.